Muffler.



e. w. HOWELL.

MUFFLER.

v APPLICATION FILED FEB. 9, 1915.

Patented Jan. 11, 1916.

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UNITED-STATES PATENT OFFICE.

GEORGE W.'HOWEI|L, OF LOS ARGELES, CALIFORNIA.

MUFFLER.

To all whom it may concern Be it known that I, GEORGE W. HOWELL, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented new and useful Improvements in Mufflers, of

which the following is'a specification.

This invention relates to mufllers or the like for internal combustion gas engines and for similarpurposes; the apparatus being applicable wherever it is desired to muflie the explosive exhaust of gases under pressure. And the invention consists in certain particulars of improvements which are hereinafter described and fully ascertained and specified.

The preferred form of apparatus embodying my invention includes a structure which controlsaspiral passage of constantly and uniformly increasing size from its inner to its outer end. The spiral form of this passage is a radial spiral rather than a longitudinal axial spiral; that is, a cross section at any point will show a volute form. The inner beginnin end of the spiral passage connects direct y'with the inner intake passage of the muflle'r, and the outer or exhaust end of the passage connects directlv,

or substantially directly, with the atmosphere. In the preferred specific form of apparatus. I utilize two oppositely placed heads which have on their inner opposite surfaces certain volute spiral grooves which have their inner ends at a certain inner limiting circumference, so that inside the spiral groove there is an ungrooved space on each of the heads. This ungrooved space represents in diameter the diameter of the intake passage of the mufller: and one of the heads has an intake opening through it of about this same diameter. Between the two heads I place a spirally. wound or coiled sheet whose opposite edges are placed in said spiral grooves. The grooves'are of such configuration that, when the whole device is assembled, the radial distance between successive convolutions of the spiral gradually and uniformly increases progressivelyoutwardly on the spiral: so that the size of the spiral passage way formed by the spiral sheet gradually and uniformly increases from the inner end of the spiral to Specification of Letters Patent.

outer end of the spiral; final communication with the atmosphere being had through these perforations.

. My detailed construction and the specificand that I do not consider that my invenv tion is primarily limited to such specific form.

In the drawings I show a. pair of heads 10 and 11 which are spaced apart a suitable distance and held together by suitable holding means, such as longitudinal bolt rods 12, or the like. Near the outer edge of each of these heads, and on their opposing inner faces, I cutcircular grooves 13; and outer cylindrical casing 1-1 is held in these grooves in the manner illustrated. This outer cylindrical casing has final exhaust openings 15 in the form of a series of perforations spaced in a longitudinal line along the casing 14.

Each of the heads 10 and 11 has, on its inner face, a spiral groove 16, the general configuration of which is shown in Fig. 2. One of the heads 11 has a central inlet opening 17 and the spiral grooves 16 begin on a circumference of approximately the same size as the inlet opening 17. The spiral grooves progress outwardly in the manner shown in Fig. 2, in volute form, the radial distance between successive vconyolutions of the groove being constantlylurduniformly Patented Jan. '11, 1916.

Application filed February 9, 1915. Serial No. 7,112.

greater progressing from the, "inner to the 16 in the manner shown; so that the spirally wound sheet is held in the same configuration as the grooves themselves.- The inner I end 20 of the sheet is on'a circumference substantially the same as or perhaps slightly larger than, the circumference of the inlet opening 17 while the outer end 20" of the spirally wound sheet is close to the outer casing 14 and in a position near the final exhaust openings 15. It will be seen that the spiral space or passage/between the convolutions of the sheet gradually and uni- :Eormly increases in size from the inner to the outer end. it will also be seen that this passage is of gradual curvature, has no abrupt turns, and has no-obstructions to the assage of the gaseetherethrough. It will e seen that there is ieitinside the spirally wound sheet an intake passage 21 of a dill ' movement outwardly with uniform expansion during that outward movement. This is an important fundamental in my construction. The gases in my muffier move outwardly to expand, as is a natural movement, rather than being torcedinwardly into a vortex as would be the case it the movement were reversed. There are no obstructions to the movement of the gas: the gas moves uniformly in a spiral .path with a smooth and easy curvature, without having to quickly or violently change its direction from the time it enters the spiral till the time it leaves and passes of? into the atmosphere. I employ a comparatively short path for the expanded gases. and llprovido my expanding passage in a device of small diameter, by the expedient of having the spiral passage Way of cross-sectional dimension relatively great in an axial direction and. relatively small in a radial direction. This is seen upon inspection of the drawings-f By cutting down the length oi the. passage way, which the gases must traverse ll thereby cut down the frictional hindrance to passage of the gases therethrough.

It is not only important that the gases be expanded uniformly and gradually and" pass in a uniform movement, unobstructed bv anv short turns. from beginning to the" end 0*? their expansion; but it is also a very desirable feature to provide adequate means for radiation of heat from the gases in order to decrease their actual volume as much as possible. This it provide by having the gases expand outwardly. The gases gradually pass over an ever inc easing area of metal, due to the fact that they pass between successive convolutions of the sheet which are gradually at a greater diameter; and the spiral sheet takes up and radiates the heat of the gases. llt is an important feature in this respect that the spiral sheet has a relatively great dimension axially; that is, the gases Lioness are conducted in a relative thin sheet between the convolutions of the spiral metal sheet of the muffler; so that the heat of the gases is readily given up to the spiral sheet and radiated thereby.

Another distinctive featurewhich I Wish to particulsrize is the size of my muffler. In proportion to the volume of gases which it handles, my muflier is very small; and one of the features of construction which enables me to make the muilier small is that the gases enter at the inside and are discharged at the outside. By this construction the interior passage 21 need be only of a size to carry the compressed gases as they enter the muflier; Whereas, if the operation were reversed and the gases passed from the outside inwardly, the inner passage 21 would necessarily be of much larger diameter in order to be of sufficient cross-sectional area to carry the gases when expanded to atmospheric pressure.

Having described a specific form of my invention, I claim:

1. A device of the character described, comprising a structure having therein a radially spiral passage of uniform axial length uniformly increasing in size from center to outside, an inlet at the center connecting with the passage at its point of minimum size, and an outlet at the outside communicating with the passage at its point of maximum size.

' 2. A device of the character described, comprising a structure embodying a sheet of uniform axial length wound in a radial spiral to form a spiral passage, the distance between successive convolutions being gradually and uniformly greater progressing outwardly on the spiral, an inlet at the center connecting with the passage at its point of minimum size, and an outlet at the outside communicating with the passage at its point of maximum size.

3. A device of the character described, comprising a structure having therein a radially spiral passage of uniform dimension in an axial direction and of gradually and uniformly increasing rad al dimension progressing outwardly, the axial dimension being relatively great as-compared with the maximum radial dimension, an inlet at the center connecting with the passage at its point of minimum size, and an outlet at the outside communicating with the passage at its point of maximum size.

4. A device of the character described, comprising an outer casing embodying a pair of circular heads and a cylindrical casing secured between them, each of the heads having a volute spiral groove in its inner surface, the radial distance between successive convolutions graduallyand uniformly increasing progressively outwardly on the spiral, a spirally wound sheet held between the heads with its edges in said grooves,

to-form a spiral passage gradually increasing in size from inside to outside, an inlet at the center connecting'with the passage at its point of minimum size, and an outlet at the outside communicating with the passage at its point of minimum size.

5. A device of the character described, comprising an outer casing embodying a pair of circular heads and a cylindrical casing secured between them, each of the heads having a volute spiral groove in its inner surface, one of said heads having a central admission opening, and said spiral grooves having their inner ends of a circumference of approximately thesize of said opening, the radial distance between successive convolutions gradually and uniformly increasing progressively outwardlv on the spiral, and a spirall wound sheet held between the heads with Its edges in said grooves, the

cross-sectional area of the space between the two last convolutions'of the spiral.

In witness that I claim the foregoing I have hereunto subscribed my name this 3rd day of February, 1915.

GEO. W. HOWELL.

Witnesses:

JAMEs T. BARKELEW, ELWooD' H. BARKELEW. 

